1
Antenna-Theory.com Presents the Spiral Antenna
Antenna-Theory.com Presents the Spiral Antenna
DATE: 2011/07/17::
2
K6ZRH- TAK-tenna antenna demo (20M shortest HF dipole spiral antenna)
K6ZRH- TAK-tenna antenna demo (20M shortest HF dipole spiral antenna)
DATE: 2009/08/25::
3
Spiral antenna
Spiral antenna
DATE: 2012/05/23::
4
What is a Helical Antenna?
What is a Helical Antenna?
DATE: 2014/06/21::
5
FPVStyle com   Aomway 11Db Helical Antenna
FPVStyle com Aomway 11Db Helical Antenna
DATE: 2014/08/20::
6
Build a 3 turn Helical antenna for 5.8ghz
Build a 3 turn Helical antenna for 5.8ghz
DATE: 2012/07/04::
7
Cavity backed log spiral antenna
Cavity backed log spiral antenna
DATE: 2013/03/11::
8
Spiral Antenna Video 3
Spiral Antenna Video 3
DATE: 2012/03/28::
9
Mini Helical Antenna 2.4GHz
Mini Helical Antenna 2.4GHz
DATE: 2013/04/06::
10
Helical Antenna
Helical Antenna
DATE: 2014/01/07::
11
FPV 5.8GHz helical antenna shootout
FPV 5.8GHz helical antenna shootout
DATE: 2014/05/02::
12
Two 5.8GHz FPV helical antennas compared
Two 5.8GHz FPV helical antennas compared
DATE: 2014/02/06::
13
Curved Spiral Antennas for Freshwater Applications
Curved Spiral Antennas for Freshwater Applications
DATE: 2015/01/20::
14
An Innovative Semicircular Spiral Antenna for On Metal Passive RFID Applications
An Innovative Semicircular Spiral Antenna for On Metal Passive RFID Applications
DATE: 2013/07/08::
15
Kc boro marble spiral antenna pink swirls
Kc boro marble spiral antenna pink swirls
DATE: 2010/12/20::
16
How to build a 5.8 GHz 4 Turn Helical Part 1
How to build a 5.8 GHz 4 Turn Helical Part 1
DATE: 2013/01/23::
17
AM Spiral Loop Antenna
AM Spiral Loop Antenna
DATE: 2010/03/16::
18
5.8GHz CP Helical antenna.
5.8GHz CP Helical antenna.
DATE: 2012/01/14::
19
6/02/2014 -- Spiral Vortex RADAR pulse in Australia - covering Exmouth Antenna Array
6/02/2014 -- Spiral Vortex RADAR pulse in Australia - covering Exmouth Antenna Array
DATE: 2014/06/02::
20
Introduction to FPV - Antenna choices (dipole, circular, helical and patch)
Introduction to FPV - Antenna choices (dipole, circular, helical and patch)
DATE: 2014/07/03::
21
Helical Antenna 5.8GHz 10 Turn
Helical Antenna 5.8GHz 10 Turn
DATE: 2013/11/08::
22
Ansys Maxwell - HFSS How to model helix circular coil for WPT
Ansys Maxwell - HFSS How to model helix circular coil for WPT
DATE: 2014/11/03::
23
Testing a DIY IBCrazy Helical Antenna for 5.8GHZ video
Testing a DIY IBCrazy Helical Antenna for 5.8GHZ video
DATE: 2012/09/22::
24
2.4 Ghz Helical Antenna -Part two
2.4 Ghz Helical Antenna -Part two
DATE: 2011/02/18::
25
My homemade 5.8 ghz helical antenna
My homemade 5.8 ghz helical antenna
DATE: 2015/04/03::
26
Helical Antenna 5 8GHz 4 Turn
Helical Antenna 5 8GHz 4 Turn
DATE: 2013/11/08::
27
2.4 Ghz Helical Antenna -Part one
2.4 Ghz Helical Antenna -Part one
DATE: 2011/02/18::
28
HF Spiral Loop Antenna video 2.
HF Spiral Loop Antenna video 2.
DATE: 2012/03/26::
29
CST MWS Tutorial 02: Geometrical Design of a Helix Antenna
CST MWS Tutorial 02: Geometrical Design of a Helix Antenna
DATE: 2011/07/06::
30
G3XBM
G3XBM's 500kHz antenna (in snow)
DATE: 2009/12/18::
31
3-Square Antenna for Wi-Fi Band
3-Square Antenna for Wi-Fi Band
DATE: 2010/11/30::
32
Infinite Spiral Longwire Antenna
Infinite Spiral Longwire Antenna
DATE: 2015/03/07::
33
HD FPV - Flying In The Dark - ( 5:30 Am - Helical Antenna Test #1 )
HD FPV - Flying In The Dark - ( 5:30 Am - Helical Antenna Test #1 )
DATE: 2013/04/14::
34
iBcrazy Helical & Crosshair Antennas for FPV
iBcrazy Helical & Crosshair Antennas for FPV
DATE: 2013/03/22::
35
HK EPP FPV test of Helical antenna 1
HK EPP FPV test of Helical antenna 1
DATE: 2012/09/04::
36
Helical vs Cross Hair FPV Ground Station Range Test - FPV Raptor Aircraft
Helical vs Cross Hair FPV Ground Station Range Test - FPV Raptor Aircraft
DATE: 2012/12/30::
37
HobbyKing Daily - Fat Shark & Immersion RC Clover Leaf Antenna
HobbyKing Daily - Fat Shark & Immersion RC Clover Leaf Antenna
DATE: 2012/08/24::
38
Antena Helice en CST Studio
Antena Helice en CST Studio
DATE: 2013/03/08::
39
Using XFdtd and XGtd to Design and Analyze a Helical Antenna on a Satellite
Using XFdtd and XGtd to Design and Analyze a Helical Antenna on a Satellite
DATE: 2010/08/16::
40
Antenna and Propagation   Polarization Measurement (Lab 5 ME1300)
Antenna and Propagation Polarization Measurement (Lab 5 ME1300)
DATE: 2014/08/01::
41
Mini wing fpv flight and Helical antenna test
Mini wing fpv flight and Helical antenna test
DATE: 2013/05/15::
42
Spiral Type Planer Antenna for Specified Low Power Radio
Spiral Type Planer Antenna for Specified Low Power Radio
DATE: 2014/11/17::
43
Modern Academy for engineering (Spiral)
Modern Academy for engineering (Spiral)
DATE: 2008/07/18::
44
DJI Phantom + DJI Zenmuse H3-2D Gimbal + go pro 3+ black + fatshark fpv with spiral antenna
DJI Phantom + DJI Zenmuse H3-2D Gimbal + go pro 3+ black + fatshark fpv with spiral antenna
DATE: 2013/11/16::
45
Magnetic loop antenna Dx Contacts Helical Loop Antenna
Magnetic loop antenna Dx Contacts Helical Loop Antenna
DATE: 2012/05/06::
46
Marconi Tesla CB Antenna` s
Marconi Tesla CB Antenna` s
DATE: 2014/02/02::
47
Drone Flight: Cerne Abbas Giant (Iris+ & GoPro 4 Black)
Drone Flight: Cerne Abbas Giant (Iris+ & GoPro 4 Black)
DATE: 2015/03/15::
48
BEST VIDEO of spiral light over Norway
BEST VIDEO of spiral light over Norway
DATE: 2009/12/11::
49
Antenna Test ::ImmersionRC 600mw vTX + IBCrazy 5-Turn Helical Receiver Antenna
Antenna Test ::ImmersionRC 600mw vTX + IBCrazy 5-Turn Helical Receiver Antenna
DATE: 2014/02/26::
50
Phantom 2 First Flight in Bishan Park
Phantom 2 First Flight in Bishan Park
DATE: 2014/01/07::
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RESULTS [51 .. 101]
From Wikipedia, the free encyclopedia
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Two-arm log spiral antenna
Not to be confused with helical antenna.

In microwave systems, a spiral antenna is a type of RF antenna. It is shaped as a two-arm spiral, or more arms may be used.[1] Spiral antennas were first described in 1956.[2] Spiral antennas belong to the class of frequency independent antennas which operate over a wide range of frequencies. Polarization, radiation pattern and impedance of such antennas remain unchanged over large bandwidth.[3] Such antennas are inherently circularly polarized with low gain. Array of spiral antennas can be used to increase the gain. Spiral antennas are reduced size antennas with its windings making it an extremely small structure. Lossy cavities are usually placed at the back to eliminate back lobes because a unidirectional pattern is usually preferred in such antennas. Spiral antennas are classified into different types; archimedean spiral, square spiral and star spiral etc. Archimedean spiral is the most popular configuration.

Working[edit]

These antennas operate in 3W way; traveling wave, fast wave and leaky wave. The traveling wave, formed on spiral arms, allows for broadband performance, fast wave due to mutual coupling phenomenon occurring between arms of spiral and leaky wave leaks the energy during propagation through the spiral arms to produce radiation. Ring theory (band theory) explains the working principle of spiral antenna. The theory states that spiral antenna radiates from a region called active region where the circumference of spiral equals wavelength.[4]

Design[edit]

Different design parameters are to be considered while designing a square spiral antenna. The parameters include spacing between the turns s, width of arm w, inner radius r_1 and outer radius r_2. The inner radius is measured from center of the spiral to center of the first turn while the outer radius is measured from center of the spiral to center of the outermost turn. Other than these design parameters, spiral antennas have lowest (f_{\text{low}} = c/2 \pi r_2) and highest (f_{\text{high}} = c/2 \pi r_1) operating frequencies. Here c corresponds to speed of light. In an (r,\theta) coordinate system, the spiral grows along the r-axis and \theta-axis simultaneously. All spirals satisfy r = a + b\theta equation where a corresponds to growth factor and b corresponds to multiplication factor.

Different designs of spiral antenna can be obtained by varying number of turns it contains, the spacing between its turns and the width of its arm. A dielectric medium is used with a specific permittivity and dimensions over which the spiral is printed. Dielectric mediums like Rogers RT Duroid help in reducing the physical size of antenna. Thin substrates with higher permittivity can achieve the same result as thick substrates with lower permittivity. The only problem with such materials is their less availability and high costs.[5]

Applications[edit]

A spiral antenna transmits EM waves having a circular polarization. It will receive linearly polarized EM waves in any orientation, but will attenuate signals received with the opposite circular polarization. A spiral antenna will reject circularly polarized waves of one type, while receiving perfectly well waves having the other polarization.

One application of spiral antennas is wideband communications. Another application of spiral antennas is monitoring of the frequency spectrum. One antenna can receive over a wide bandwidth, for example a ratio 5:1 between the maximum and minimum frequency. Usually a pair of spiral antennas are used in this application, having identical parameters except the polarization, which is opposite (one is right-hand, the other left-hand oriented). Spiral antennas are useful for microwave direction-finding.[6]

Elements[edit]

The antenna includes two conductive spirals or arms, extending from the center outwards. The antenna may be a flat disc, with conductors resembling a pair of loosely-nested clock springs, or the spirals may extend in a three-dimensional shape like a screw thread. The direction of rotation of the spiral defines the direction of antenna polarization. Additional spirals may be included as well, to form a multi-spiral structure. Usually the spiral is cavity-backed, that is there is a cavity of air or non-conductive material or vacuum, surrounded by conductive walls; the cavity changes the antenna pattern to a unidirectional shape. The output of the antenna is a balanced line. If one input or output line is desired, for example a coaxial line, then a balun or other device is added to so transform the signals.

References[edit]

  1. ^ Richard C. Johnson, Henry Jasik, Antenna Engineering Handbook, Second Edition, ISBN 0-07-032291-0, 1961, Chapter 14-2
  2. ^ Orr, William I. (1976). Beam Antenna Handbook, 5th Edition. Radio Publications, Inc. pp. 185–186. 
  3. ^ Paul E. Mayes, “Frequency-Independent Antennas and Broad-Band Derivatives Thereof”, Proceedings of the IEEE, Volume: 80 , Issue: 1, Digital Object Identifier: 10.1109/5.119570, Publication Year: 1992, Page(s): 103 - 112
  4. ^ A. Mehta, D. Mirshekar-Syahkal and H. Nakano , “Beam adaptive single arm rectangular spiral antenna with switches”, Microwaves, Antennas and Propagation, IEE Proceedings - Volume: 153 , Issue: 1, Digital Object Identifier: 10.1049/ip-map:20050045, Publication Year: 2006 , Page(s): 13 – 18
  5. ^ Asad, M., Gilani, J., Khalid, A. and Iqbal, M.S., “Optimizing Q factor of square spiral antenna ”, PACCS 2010, Page(s): 227 - 230
  6. ^ Stephen E. Lipsky "Microwave Passive Direction Finding " SciTech Publishing, 2004 ISBN 1-891121-23-5 page 40

"Practical antenna" references[edit]

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